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and in the essential oil of the rind. From the first are manufactured 

 the citrate and citric acid of commerce. 



The raw juices of all the different varieties of the citrus species, 

 except that of the bergamot, are available for commerce, but the juice 

 of the lemon is the most highly prized, on account of the greater 

 amount of acidity it contains and of its durability. But the raw juice, 

 " argo crudo," however rich in acid particles can never vie in this 

 respect with the same juice in a concentrated form, with the " argo 

 cotto," in which form it enjoys besides a great superiority over un- 

 condensed juice, in duriability and in reduction of volume. This 

 concentrated juice is prepared in the following manner. The juice 

 is first of all clarified by being left to stand, then boiled in large chaldrons 

 of tinned copper, one-third full, and the boiling liquid frequently 

 stirred with an iron rod having its head wrapped in some common 

 canvas or in rags which serve thus to keep the bottom of the boiler 

 clear of all sedimentary matter ; those necessary additions to the boiling 

 liquid, which the constant evaporation of the aqueous particles renders 

 expedient, are supplied from smaller supplementary boilers in which 

 the liquid is kept sufficiently hot, to hinder any interruption in the 

 ebullition of the juice contained in the large vessels. When the 

 required density is attained, a point which is easily ascertained through 

 the medium of the citrometer, it is poured into vats to cool, and finally 

 drawn off through ordinary funnels into casks. Eight measures of raw 

 juice are needed to produce one of concentrated at 60° of the citro- 

 meter, and this again when pure will contain about 30 per cent, of 

 citric acid. 



The adulteration of the acid or juice is facilitated by the ready 

 absorption of certain well-known and easily obtainable substances, 

 which increase the weight of the acid juice when concentrated. The 

 most commonly employed substances for the purpose of adulteration 

 are tartaric acid, chloride of sodium, and sulphuric acid. The methods 

 employed in Sicily, in order to detect the cheat, if not so scientific and 

 perhaps less acurate than those in use in England, are at least in- 

 expensive, simple, and sufficiently effective. Thus the tartaric acid is 

 easily detected by the addition of acetic acid and acetate of potassium, 

 which combine with the tartaric acid to form tartrate of potash or cream 

 of tartar. The presence of chloride of sodium is revealed by a solution 

 of nitrate of silver, which decomposes the salt and attracts the chlorine. 

 The sulphuric acid is likewise discovered in the juice by a less simple 

 process. The numerous uses to which the juice, raw or concentrated, 

 is adapted are well-known, but the two principal uses are those to 

 which it is put, under the modified forms of citrate of lime and citric 

 acid, the former being but a preliminary step towards the fabrication of 

 the latter, which is the ultimate object of the produce of citrate, 

 although in some regions where it is fabricated independently of its 

 connection with citric acid, it forms a principal object of exportation. 

 This separate production and exportation of citrate of lime prevails, 

 especially throughout those regions, for which nature has done so much 

 and men so little, in which the raw materials are so abundant ar.d yet 

 so little used that we witness yearly large shipments of concentrated 

 juice and even of citrate of lime from the land of the orange, lemon, and 

 sulphur, to those distaut centres of manufacturing and commercial 



